This slender little perennial likes to grow on heathery heaths and poor grasslands, often around sphagnum moss.The name Milkwort was coined by a Greek botanist who claimed that the plant increased milk yield, whether in cows or humans is not clear. In traditional medicine it was used to treat bronchitis.
It has slender upright stems, glabrous and often reddish in appearance. The leaves grow in opposite pairs, in a crowd at the base, then thinning out further up the stem where they become less uniformly opposite. The opposite lower leaves are a feature which distinguishes Heath Milkwort from Common Milkwort (P.vulgaris) which has alternating leaves. But whereas Heath Milkwort likes an acid soil, the common variety prefers a chalky alkaline soil, so the two seldom meet. The leaves are narrowly oval with smooth edges and short, about 1 to 2cm long.
The flowers are tiny, about 5mm long with 5 sepals, 2 of which are larger, looking like 2 petals. Inside these are 3 smaller whitish petals fused at the base and frilled at the tips. The flowers are often sky blue, but pink and white varieties can be found. They grow on thin spikes of 3 to 10 flowers.